We all know how versatile Android already is, Canonical are taking that versatility and putting it to a whole new level, by bringing Ubuntu to Android.
The idea is to get the whole Ubuntu experience through any monitor, meaning you literally have PC in your pocket. Ubuntu and Android will work together in the phone so you'll still be able to use Android on your phone but will see Ubuntu on your desktop screen.
Before you get too excited though, it isn't available to the public directly. Only mobile phone manufacturers and carriers are able to get hold of Ubuntu.
Ubuntu will only work best with high-end Android phones, devices such as the Galaxy Nexus and Samsung Galaxy S2. But with quad-core devices most probably coming out this year, Ubuntu will be great for those sorts of devices.
If manufacturers were to take on Ubuntu, Canonical say that it would boost the sales of Android devices. However, I'm not too sure about this one. It may be attractive to hardcore smartphone users but the average consumer wouldn't have a clue what Ubuntu is. Unless there was some serious marketing done, the average consumer couldn't care less.
It's definitely quite an interesting topic and something which could (not will) change the way we use smartphones. Instead of having to carry around netbooks and laptops, we can have a PC in our pocket. But then you don't have the screen, like you do with laptops. So it kind of defeats the objective.
You can find out a lot more information about it at their website - Ubuntu